Fuel system for internal combustion engines



April 23, 1963 E. L. RAPPLEAN FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 23, 1959 4 Sheets-Sheet 1 INVENTOR. EUGENE L. RAPPLEAN ATTORNEY A ril 23, 1963 E. 1.. RAPPLEAN FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 23, 1959 4 Sheets-Sheet 2 m J w 4 6 M I H 4 a .W m w 4 H 9 1 5 7 2 G W/ N U w z 6 H T n wwwmw 1 Z a 7 ".7 3 3\\ J \k- I U..- Jl i/ m 9 z a a E s 2 I Ill a w 5 Mm I- 1 m i J M m 9 i y M M :2 W /A z E v .m 9 E I/ INVENTOR. EUGENE L. RAPPLEAN ATTORNEY April 1963 E. RAPPLEAN 3,086,756

FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 25, 1959 4 Sheets-Sheet 3 F l G. 5

INVENTOR.

EUGENE L. RAPPLEAN ATTORNEY April 23, 1963 E. L. RAPPLEAN FUEL SYSTEM FOR INTERNAL COMBUSTION ENGINES 4 Sheets-Sheet 4 Filed Oct. 25, 1959 INVENTOR. EUGENE L. RAPPLEAN W/QBW ATTORNEY United States Patent 3,086,756 FUEL SYSTEM FOR INTERNAL COMBUSTEQN ENGINES Eugene L. Rappiean, Ferguson, Mm, assignor to ACE Industries, Incorporated, New York, N.Y., 'a corporation of New Jersey Filed Oct. 23, 1959, Ser. No. 848,351 7 Claims. (Cl. 26123) This invention relates to fuel systems for internal combustion engines and more particularly to a fuel system embodying one or more floatless carburetors.

The present invention is particularly adapted for use on multi-cylinder outboard motors provided with a plurality of carburetors.

Heretofore, multi-cylinder outboard motors have been provided with conventional float type carburetors in which the fuel level within a fuel bowl is determined by a float controlled needle valve. During rapid travel of a boat over rough water, it is not possible to maintain a constant fuel level within a carburetor fuel bowl provided with a float controlled needle valve. When a multicylinder outboard motor is equipped with several float type carburetors, it is obviously impossible to maintain a constant fuel level in each of the several fuel bowls to insure a uniform supply of fuel to the engine.

It is, therefore, an object of the invention to provide a fuel system embodying a floatless carburetor adapted to provide a fuel mixture to suit engine requirements.

Another object of the invention resides in the provision of a fuel system comprising a plurality of floatless carburetors provided with fuel bowls, and means to maintain a substantially constant fuel level in each of the several fuel bowls to insure an equal delivery of fuel from the several carburetors.

A further object of the invention resides in the provision of a multi-carburetor fuel system for an engine wherein several floatless carburetors are supplied with fuel from a common fuel pump actuated by the engine, the pump being operable to supply fuel to the several carburetors in excess of engine requirements, and such excess fuel being returned to the fuel tank through overflow pipes leading thereto from the carburetor fuel bowls.

Another object of the invention resides in the provision of an internal combustion engine fuel system comprising a diaphragm pump operable responsive to pressure pulsations in the engine crankcase to supply fuel to several interconnected floatless carburetor bowls in excess of fuel requirements of the engine.

Another object of the invention resides in the provision of a floatless carburetor adapted to more accurately control the fuel mixture supplied to an engine to thereby effect greater economy of operation and improved engine performance.

The invention embodies other novel features, details of construction and arrangement of parts which are hereinafter set forth in the specification and claims and illustrated in the accompanying drawing, wherein:

FIG. 1 is a plan view of the top carburetor of a plurality of carburetors, in accordance with the invention, mounted one above the other and attached to the intake manifold of an engine.

FIG. 2 is an elevation showing one side of one of the carburetors of FIG. 1.

FIG. 3 is a view in elevation showing the opposite sides of the lowest two carburetors of FIG. 1 with only a partial showing of the lowest carburetor.

FIG. 4 is a longitudinal section taken along the line 4-4 of FIG. 1.

FIG. 5 is a transverse section taken along the line 55 of FIG. 2.

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FIG. 6 is a section illustrating a diaphragm pump.

FIG. 7 is a perspective view illustrating a conventional three cylinder outboard motor provided with a fuel system embodying features of the invention.

Referring now to the drawings for a better understanding of the invention, the carburetor C is shown as comprising a body 2 having a horizontal mixture conduit 3 provided with an air inlet 4, an outlet 6, and a venturi 7 having a throat 8. A flange 1 is provided on the outlet end of the body for attachment to an engine inlet manifold 5.

A choke valve shaft 9 is journaled in bearing apertures formed in the body 2 to support a choke valve 11 for pivotal movement within the air inlet 4. The choke valve 11 is normally maintained in its full open position, as indicated in FIG. :1, by means of a torsion spring '12 having one end thereof secured to the shaft *9 and its other end secured to the body 2.. The choke valve 11 is adapted to be pivoted to its closed or choke position by manual movement of an arm 13 secured to one end of the choke shaft 9.

A throttle shaft 14 is journaled in bearing apertures formed in the 'body 2 to support a throttle valve 16 for pivotal movement in the outlet 6, the shaft being engaged against axial movement relative to the body 2 by means of a plate 17 secured to the body by a screw 18 and having an end thereof engaged in an annular groove 19 formed in the shaft. A manually operable control arm 21 is secured to one end of the throttle shaft 14 to control the proportion and quantity of fuel and air supplied to the engine. The throttle valve 14 is biased toward its closed position by means of a helical torsion spring 22 having one of its ends engaging the body 2 and its other end engaging the control arm 21.

The body 2 is provided with a downwardly projecting tubular stem 23 having its lower end internally threaded at 24 for engagement with the lower externally threaded end 25 of a main fuel nozzle 26 as illustrated in FIG. 4. The lower end of the nozzle is slotted at 27 for engagement by a screw driver during assembly to rotate the nozzle into tight lea'kproof engagement against an annular shoulder 28. The portion of the nozzle between its threaded end 25 and the shoulder 28 is reduced in diameter to define with the stem 23 a fuel well 29. A plurality of ports 31 are formed in the nozzle for the passage of fuel into and out of the lower end of the well 29, and an air bleed passage 32 is formed in the body 2 leading from atmosphere to the upper end of the well.

The upper end of the main fuel nozzle 26 projects upwardly into the venturi 7 posterior to the throat 8 and is provided with a plurality of low speed ports 33. A fuel metering orifice 34 is formed in the lower end of the main fuel nozzle 26 to receive the lower end 36 of a metering rod 37. The lower end of the metering rod 37 engages a head pin 38 which is resiliently supported upon a helical compression spring 39 seated at its lower end in a fuel bowl mounting screw 41. The upper end of the metering rod 37 extends through a bearing 40 press-fitted into an opening 42 in the body 2.

The lower portion of the body 2 is formed with a downwardly projecting annular flange 43 having a recess 44 therein to receive the rim portion of a cup-shape fuel bowl 46, the bottom 45 of the bowl having an aperture 47 to receive the screw 41, and an annular inturned bead 48 concentric with said aperture. During assembly, the screw 41 first engages the bowl rim against a gasket 49 in the recess 44, and then forces the bowl bottom 45 against the stem 23.

An air vent leads from atmosphere through the body 2 to the bowl. Fuel is supplied from a tank T through a conduit 57 and pump P to the fuel inlet 54. Fuel passes from the bowl through ports 55 into a chamber 60 in the stem 23 below the orifice 34.

The fuel level in the bowl 46 is maintained substantially constant by means of a standpipe 51 which is. secured to the bowl bottom and connected to a fuel return conduit An idle fuel system is shown as comprising a hollow idle tube 59 extending vertically from within the fuel bowl 46 through the venturi throat 8 to an idle passage 61 in the body 2, the lower end of the tube 59 being disposed below the fuel level in the bowl and provided with a restricted orifice 62. The idle passage 61 extends to an idle port 63 leading into the mixture conduit 3 anterior to the edge of the throttle valve 16 when the latter is in its closed position. Apertures 64 are provided in'the throttle valve 16 for the passage of air when the latter is in its closed position. An idle adjustment screw 66 is threaded into the body 2 to regulate the flow of fuel through the idle passage 61.

A cam 67 having an inclined surface 68 is provided on the control arm 21 for slidable engagement along the upper end of the metering rod 37 responsive to rotational movement of the control arm, whereby the metering rod is moved axially to vary the quantity of fuel passing through the orifice 34. The lower end of the metering rod may be provided with one'or more sections of different diameters, as shown in FIG. 4, or may be formed with a long tapering surface, whereby the flow area through the orifice 34 may be varied responsive to axial movement of the metering rod.

In the operation of the carburetor thus shown and described, fuel is forced from the tank T through the conduit 57 to the pump P, and thence into the fuel bowl 46. To maintain the fuel at a predetermined level within the bowl, excess fuel is removed from the bowl through the standpipe 51 and conduit 52.

During idle operation of an engine, the throttle valve 16 is in its closed position and fuel is supplied to themixture conduit 3 through the idle tube 59, passage 61, and idle port 63, under control of the idle adjustment screw 66. The-effect a slight increase in engine speed, the control arm 21 is manually pivoted to move the throttle valve .16 to a part open position to cause fuel to be drawn upwardly through the main nozzle 26 and out through the ports 33 into the mixing conduit 3.

Further gradual pivotal movement of the control arm 21 moves the throttle valve 16 toward its full open position and permits the spring 39 to raise the metering rod 37 as the latter passes along the inclined surface 68 on the cam 67 to thereby increase the flow area and the volume of fuel flowing through the orifice 34 for passage upwardly and out through the upper end of the main nozzle 26 into the center of the mixture conduit 3.

When the throttle valve 16 is opened quickly to provide rapid acceleration of an engine, additional fuel and air is drawn from the well 29 through the openings 31 into the main nozzle 26 for discharge therefrom into the mixing conduit '3.

By providing a manually operable mechanical means for simultaneously operating the throttle valve and metering rod, the quantity and proportion of fuel and air may be accurately controlled to effect a material saving of from to 30% in fuel and an improvement in engine performance during'idling, part throttle, acceleration, and full throttle. In the operation of a boat equipped, for example, with two 50 or 60 horsepower engines it will be appreciated that such a saving in fuel is of major importance, as it decreases the cost of opera-tion and permits an increase in the range a boat'may travel when supplied with a predetermined quantity of fuel.

'FIG. 6 illustrates a conventional diaphragm pump P operable responsive to pressure pulsations within the crankcase K of an engine E. The pump is shown as comprising a housing body 76 having a flexible diaphragm 77 secured thereto by a cover 78 to define a pump chamber 79 and a pressure pulsation chamber 81. The pump chamber 79 is provided with a fuel inlet 82 and an outlet 33 having inlet and outlet check valves 84 and 86, respectively, therein. A conduit 87 leads from the pulsa tion chamber 81 to the engine crankcase K.

In FIG. 7, a conventional multi-cylinder outboard motor is shown as provided with a fuel system embodying several identical floatless carburetors C, C1 and C2 mounted on -a common intake manifold and supplied with fuel from a tank T by a pump P interposed in the fuel supply conduit 57. The pump P is preferably of the diaphragm type illustrated in FIG. 6 and operated by pressure pulsations from the engine crankcase K to supply fuel to the several floatless carburetors in excess of engine requirements, such excess fuel being continuously returned to the fuel tank T during operation of the engine.

As illustrated in FIG. 7, the carburetors C, C1 and C2 are preferably arranged in series in the fuel system whereby fuel is transferred from the tank T to the uppermost carburetor C through the conduit 57, and excess fuel passes downwardly through the standpipe 51 and conduit 52 to a second carburetor C1. Excess fuel supplied to the carburetor C1 flows downwardly through a standpipe 51 and conduit 52a to a third carburetor C2; and excess fuel in the third carburetor flows downwardly from the fuel bowl through a standpipe 51 and conduit 52b back to the fuel tank T.

By providing identical floatless carburetors with standpipes, it is possible to control the fuel level within the several carburetors to insure a proper uniform fuel mixture to a common engine inlet manifold. It is contemplated that the throttle valves of the several carburetors may be actuated by a common control means, such as a manually rotatable shaft 101 ('FIG. 1) having arms 102 secured thereto, each arm having a lug engaging a cam surface 103 on a throttle actuating arm 21.

When a floatless carburetor of the type shown and described is applied to an outboard motor for boats, the standpipe 51 is preferably located close to the stem 23 and between the stem 23 and the front end of the boat to maintain a high fuel level in the bowl 46 during rising of the bow of a high speed boat.

Certain structures have been described herein which will fulfill all the objects of the present invention, but it is contemplated that other modifications will be obvious to those skilled in the art which come within the scope of the invention as defined by the appended claims.

I claim:

1. A fuel system for an internal combustion engine having an intake manifold, said system comprising a plutrality of floatless carburetors arranged one above the other, each carburetor comprising a body having a mixture conduit adapted to supply a fuel mixture to the intake manifold, a fuel bowl having a fuel inlet and an overflow outlet for maintaining a predetermined level of fuel in the bowl, a main fuel nozzle to supply fuel from said bowl to said mixture conduit, a fuel source, 'means to pump fuel in excess of engine requirements from said source into the fuel bowl of an upper one of said carburetors, a gravity feed conduit leading from the overflow outlet of said upper carburetor to the fuel bowl inlet of an adjacent lower carburetor, and a return conduit leading from the overflow outlet of said lower carburetor to said fuel source.

2. An internal combustion engine comprising an intake manifold, a fuel source, a plurality of floatless carburetors arranged one above the other, each carburetor having a mixture conduit communicating with said intake manifold, and a fuel bowl having a fuel inlet and an overflow outlet for maintaining a predetermined level of fuel in the bowl, means to supply fuel in excess of engine requirements from said fuel source to the fuel bowl of an upper one of said carburetors, a gravity feed conduit leading from the overflow outlet of said fuel bowl of said upper carburetor to the inlet of a fuel bowl of a lower one of said carburetors, and a return conduit leading from the overflow outlet of said lower carburetor to return excess fuel to said fuel source.

3. A multi-cylinder two cycle internal combustion engine comprising an intake manifold, a fuel tank, a plurality of floatless carburetors arranged one above the other and above said fuel tank, each carburetor having a mixture conduit communicating with said intake manifold, and a fuel bowl having a fuel inlet and an overflow outlet for maintaining a predetermined level of fuel in the bowl, pump means to supply fuel in excess of engine requirements from said tank upwardly to the fuel bowl of an upper one of said carburetors, a gravity feed conduit leading from the outlet of said fuel bowl of said upper carburetor to the inlet of a fuel bowl of a lower carburetor, and a return conduit leading from the overflow outlet of said lower carburetor to return excess fuel by gravity to said fuel tank, said pump means comprising a diaphragm operably responsive to pressure pulsations from the engine.

4. In a fuel system for an internal combustion engine, a floatless carburetor comprising a mixture conduit, a throttle valve in said conduit, a fuel bowl having a fuel inlet and an overflow outlet to maintain a predetermined level of fuel in the bowl, a main fuel system to supply fuel from said bowl to said mixture conduit, a movable fuel metering rod controlling the flow of fuel through said main fuel system, an idle fuel system to supply fuel from said bowl to said mixture conduit, a fuel tank, a pump operable to transfer fuel from said tank to said fuel bowl in excess of engine requirements, and a fuel return conduit for the flow of excess fuel from the overflow outlet back to the fuel tank, said pump comprising a flexible diaphragm forming a partition between a pump chamber and a pulsation chamber, and means adapted to provide a passageway for pressure pulsations from an engine crankcase to said pulsation chamber to impart movement to said diaphragm.

5. In an internal combustion engine, a fuel system comprising a tank, a plurality of floatless carburetors having fuel bowls, each bowl having a fuel inlet and an overflow fuel outlet, the fuel outlet of one carburetor being connected to the fuel inlet of another carburetor, means to supply fuel to said one carburetor, and means to return excess fuel from said other carburetor to said tank.

6. A fuel system for an internal combustion engine, said system comprising a fuel source and a plurality of floatless carburetors arranged one above the other, each of said carburetors including a mixture conduit, a throttle valve in said mixture conduit, a fuel bowl in each of said carburetors having a fuel inlet and an overflow outlet to maintain a predetermined level of fuel in the bowl, a fuel passage in each of said carburetors including a main fuel nozzle leading from said bowl to said mixture conduit, means in said passage defining a restricted orifice for the flow of fuel from said bowl to said nozzle, a fuel metering rod in each one of said carburetors having one end thereof extending through said orifice, said one metering rod end having different sized stepped portions movable successively through said orifice to vary the flow of fuel therethrough, pump means to supply fuel to said bowl of each of said carburetors in excess of engine requirements from said source into the fuel bowl of an upper one of said carburetors, a gravity feed conduit leading from the overflow outlet of said upper carburetor to the fuel bowl inlet of an adjacent lower carburetor, and a return conduit leading from the overflow outlet of said lower carburetor to said fuel source, and common means to actuate said metering rods simultaneously.

7. A fuel system for an internal combustion engine, said system comprising a source of fuel and a plurality of floatless carburetors arranged one above the other, each of said carburetors including a mixture conduit, a throttle valve in said mixture conduit, a fuel bowl in each of said carburetors having a fuel inlet and an overflow outlet to maintain a predetermined level of fuel in the bowl, a fuel passage in each of said carburetors including a main fuel nozzle leading from said bowl to said mixture conduit, means in said passage defining a restricted orifice for the flow of fuel from said bowl to said nozzle, a fuel metering rod in each one of said carburetors having one end thereof extending through said orifice, said one metering rod end having difierent sized stepped portions movable successively through said orifice to vary the flow of fuel therethrough, pump means to supply fuel to said bowl of each of said carburetors in excess of engine requirements from said source into the fuel bowl of an upper one of said carburetors, a gravity feed conduit leading from the overflow outlet of said upper carburetor to the fuel bowl inlet of an adjacent lower carburetor, and a return conduit leading from the overflow outlet of said lower carburetor to said fuel source, and common means to actuate said metering rods simultaneously, said common means including a different cam fixed to each of said throttle valves respectively and 0p eratively connected to a corresponding one of said metering rods and a lever means for operating said cams simultaneously.

References Cited in the file of this patent UNITED STATES PATENTS 1,612,352 Boehner Dec. 28, 1956 2,811,862 Libby Nov. 5, 1957 2,846,203 Voss et a1. Aug. 5, 1958 2,964,303 Smith et a1. Dec. 13, 1960 2,986,381 Jones May 30, 1961 

1. A FUEL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING AN INTAKE MANIFOLD, SAID SYSTEM COMPRISING A PLURALITY OF FLOATLESS CARBURETORS ARRANGED ONE ABOVE THE OTHER, EACH CARBURETOR COMPRISING A BODY HAVING A MIXTURE CONDUIT ADAPTED TO SUPPLY A FUEL MIXTURE TO THE INTAKE MANIFOLD, A FUEL BOWL HAVING A FUEL INLET AND AN OVERFLOW OUTLET FOR MAINTAINING A PREDETERMINED LEVEL OF FUEL IN THE BOWL, A MAIN FUEL NOZZLE TO SUPPLY FUEL FROM SAID BOWL TO SAID MIXTURE CONDUIT, A FUEL SOURCE, MEANS TO PUMP FUEL IN EXCESS OF ENGINE REQUIREMENTS FROM SAID SOURCE INTO THE FUEL BOWL OF AN UPPER ONE OF SAID CARBURETORS, A GRAVITY FEED CONDUIT LEADING FROM THE OVERFLOW OUTLET OF SAID UPPER CARBURETOR TO THE FUEL BOWL INLET OF AN ADJACENT LOWER CARBURETOR, AND A RETURN CONDUIT LEAD- 